v0.2.0: Temperature controlled lasers, user level control and access any laser setting conveniently

- Added support for temperature tuned lasers, automatic discovery of whether 
  the laser is wavelength or temperature controlled
- Adding a `client` attribute to the `DLCcontrol` class to access any laser
  attribute
- Methods for setting and getting the user level for enabling change of
  restricted parameters
- Parameters dictionary now includes timestamp of the parameter set
- Black formatting

Initial release

The DLCcontrol class can read and control:

• laser current on/off
• wavelength setpoint
• analogue remote control settings (can control laser current and/or piezo simultaneously)
  • enable/disable
  • select input channel
  • set multiplier factor of the input voltage
• internal scan settings (both for scanning the piezo and laser current)
  • scan start
  • scan end
  • scan offset
  • scan amplitude

The class will check that wavelength setpoint and internal scan settings are within acceptable ranges (and raise a OutOfRangeError if not).

The module also provides some convenient dictionaries with all the settings it can modify, these dictionaries can be saved with measurement data to make sure all settings are recorded. The DLCcontrol class can dump these dicts to json files.